Induction of antibodies neutralizing the Shiga-like toxin IIv (SLTIIv) in piglets was attempted by immunization of suckling piglets intramuscularly with the SLTII toxoid completed with a lipoid adjuvant or aluminium hydroxide adjuvant. The piglets coming from dams with detectable antibodies neutralizing SLTII and SLTIIv produced antibodies to SLTII, but only a part of them produced antibodies to SLTIIv. The piglets coming from darns free of the neutralizing antibodies did not produce any neutralizing antibodies following the immunization with the toroid completed with the aluminium hydroxide adjuvant. The production of antibodies neutralizing SLTIIv was demonstrable in 10 of the 54 immunized piglets. It is concluded that the immunization of piglets with SLTII did not induce sufficient production of antibodies neutralizing SLTIIv